This invention relates to directional hydrophones and especially to a transducer/circuit combination which provides a (cos.sup.2 .theta.) output over a broad frequency band.
A free-flooded, circumferentially polarized ring transducer can be used to generate a (cos.sup.2 .theta.) directivity pattern. However, this transducer operates only over a limited band of frequencies. Also, to make a circumferentially polarized ring, the ring must either be segmented or have stripe electrodes on the inner and outer surfaces. In practice, good nulls at .theta.=90.degree. are not obtained with a circumferentially polarized ring transducer. The nulls at 90.degree. are only 10 or 15 dB below the response at 0.degree.. A ring transducer which could provide well-defined nulls and broadband response would be desirable.